1. Field of Invention
This invention relates to optical communication. More particularly, this invention relates to systems and methods using optical switches for adding and dropping channels from an optical transmission medium.
2. Description of Related Art
In current optical communication systems, multiple channels are multiplexed onto a single optical transmission medium using multiplexing techniques, such as wavelength-division-multiplexing (WDM). WDM can combine a plurality of communication channels, in the form of discrete wavelengths, onto a single optical fiber. As multiplexing techniques improve, an increasing number of channels are being transmitted on a single optical fiber or group of optical fibers. As the number of channels increase, so too does the need for an ability to add and/or drop a portion of the channels to and/or from the transmission medium.
Current communication systems can use an opto-electronic regeneration technique to add and drop channels from a transmission system. With such a technique, in order to receive or transmit data on the optical network using WDM, a node of the network can include at least one optical sensor that receives the optical signal at one or more wavelengths. The optical sensor can include an optical-electrical converter that can convert the optical signal to electrical signals corresponding to the received optical signals. Adding and/or dropping of the signals can then be performed electronically by processing the electrical signals in the electrical domain. The resulting electrical signal can then be modulated onto the network using an electro-optical converter. Such Optical-Electrical-Optical (OEO) conversion can be very complex, costly and time consuming.
Additionally, optical wavelength add/drop multiplexers (OADM) can be used in WDM transmission systems. Currently, it has been well recognized that OADMs are needed to avoid the complex and costly OEO conversions. However, currently available OADMs are generally fixed. In other words, a given incoming channel (wavelength) is only associated with a fixed add/drop port. Such a device lacks “client-configurability” and therefore severely limits the selection of which channels to add/drop for a client.
Therefore, there exists a need for a device to add and drop channels from a transmission medium that can be readily configured according to the needs of a client.